/* A simple server in the internet domain using TCP
   The port number is passed as an argument */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/types.h> 
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <errno.h>

#define NPACK 10
#define BUFSIZE 512

void error(char *msg)
{
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[])
{
    int sockfd, portno;
    socklen_t  clilen;
    char buffer[BUFSIZE+1];
    struct sockaddr_in serv_addr, cli_addr;

    if (argc < 2) {
        fprintf(stderr,"ERROR, no port provided\n");
        exit(1);
    }

    sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
    if (sockfd < 0) 
        error("ERROR opening socket");

    bzero((char *) &serv_addr, sizeof(serv_addr));
    portno = atoi(argv[1]);
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(portno);

    if (bind(sockfd, (struct sockaddr *) &serv_addr,
                sizeof(serv_addr)) < 0) 
        error("ERROR on binding");

    clilen = sizeof(cli_addr);
    for(int i = 0; i < NPACK; ++i) {
        if(recvfrom(sockfd, buffer, BUFSIZE, 0, (struct sockaddr *)&cli_addr, (socklen_t *)&clilen) == -1) {
            error("error on recvfrom");
        }
        printf("received packet from %s:%d\n data: %s\n\n",
                inet_ntoa(cli_addr.sin_addr), 
                ntohs(cli_addr.sin_port),
                buffer);
    }
    close(sockfd);
    return 0; 
}
